title: Objective quantification of arm rigidity in MPTP-treated primates.
abstract: Rigidity is a cardinal symptom of Parkinson's disease and is frequently used as an outcome measure in clinical and non-human primate studies examining the effects of medication or surgical intervention. A limitation of current rigidity assessment methods is that they are inherently subjective. To better understand the physiological mechanisms of rigidity and how various therapeutic approaches work, a more objective and quantitative method is needed. In this study, an automated arm rigidity testing (ART) system was developed to objectively quantify rigidity while the primate's limb was moved between two user-specified angles. Recordings of normal force versus elbow-angle were categorized according to area and slope. These quantitative measures of rigidity were investigated in three rhesus macaque monkeys treated with 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine and compared with clinical assessment methods. The ART system incorporates electromyographical recordings that can detect and differentiate active from actual resistance. The ART system detected significant changes in rigidity measures following administration of apomorphine or deep brain stimulation of the globus pallidus internus. The most sensitive measures were total area, extension slope, and flexion slope. The ART system provides precise and reliable measures of rigidity that are objective and quantitative.
authors.affiliation: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH, USA.
authors.forename: Thomas O
authors.initials: TO
authors.lastname: Mera
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Johnson
authors.forename: Darrin
authors.initials: D
authors.lastname: Rothe
authors.forename: Jianyu
authors.initials: J
authors.lastname: Zhang
authors.forename: Weidong
authors.initials: W
authors.lastname: Xu
authors.forename: Debabrata
authors.initials: D
authors.lastname: Ghosh
authors.forename: Jerrold
authors.initials: J
authors.lastname: Vitek
authors.forename: Jay L
authors.initials: JL
authors.lastname: Alberts
mesh_terms: D000818:Animals; D000978:Antiparkinson Agents / Q000494:pharmacology; D001058:Apomorphine / Q000494:pharmacology; D001132:Arm / Q000503:physiopathology*; D046690:Deep Brain Stimulation / Q000379:methods; D004195:Disease Models, Animal; D004576:Electromyography / Q000379:methods; D001330:Electronic Data Processing; D005260:Female; D020267:MPTP Poisoning / Q000150:complications* / Q000473:pathology* / Q000628:therapy; D008253:Macaca mulatta; D009127:Muscle Rigidity / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000503:physiopathology; D016059:Range of Motion, Articular / Q000187:drug effects / Q000502:physiology
chemical_list: D000978:Antiparkinson Agents; D001058:Apomorphine